A power converter built in a vehicle power generator is connected between a rotating electrical machine and a battery or a vehicle electric load. The power converter rectifies AC power output from the rotating electrical machine to convert the AC power into DC power, and supplies the DC power to the battery or the vehicle electric load.
In recent years, for the purposes of increasing a request of the amount of generated power and achieving noise reduction, higher efficiency, and the like, it has been proposed to use a field winding type rotating electrical machine including a plurality of sets of armature windings as a rotating electrical machine, or proposed to employ MOSFETs as switching elements of a bridge circuit for AC-DC conversion to perform so-called synchronous rectification (see, for example, Patent Literature 1).
By the way, in the case of abrupt load dump, such as when a cable connecting the power generator and the battery to each other is disconnected during power generation, generated power becomes excessive temporarily, with the result that a high voltage (load dump surge) may be generated at a B-terminal of the power generator.
As a countermeasure, there has been known an AC power generator that suppresses the load dump surge with use of avalanche breakdown of the MOSFET (see, for example, Patent Literature 2).
Further, there has been known a controller for a field winding type rotating electrical machine, which suppresses the load dump surge by turning on all switching elements of a negative arm or a positive arm of an inverter to short-circuit the armature windings (see, for example, Patent Literature 3).